Microbiology

• What is the main practical objective of the experiment?

  Investigating the effect of antiseptics on bacteria
• What apparatus is needed for the experiment?

  • Disinfectant solution/alcohol
  • Bunsen burner
  • Sterile petri dish with nutrient agar
  • Inoculating loop
  • Tape
  • Marker pen
  • Culture of bacterium
  • Tweezers
  • Filter paper discs
  • Antiseptics
  • Incubator
• Why is it important to sterilize the inoculating loop?

  To prevent contamination of the bacteria
• How should the petri dish be labeled before inoculation?

  With date, initials, and bacteria used
• What is the purpose of dividing the petri dish into sections?

  To test different antibiotics in each section
• What technique is used to inoculate the agar dish?

  Zigzag streaks
• Why should the lid of the petri dish be fixed with tape?

  To prevent contamination while allowing airflow
• What temperature should the agar be incubated at?

  25 degrees Celsius
• What is the risk of incubating above 25 degrees?

  Increases risk of culturing harmful pathogens
• How is the diameter of the clear zone measured?

  Using a ruler across the center of the disc
• What are the independent and dependent variables in this experiment?

  Independent: type of antibiotic; Dependent: diameter of clear zone
• What are the important control variables in the experiment?

  • Type of bacteria
  • Size of antiseptic disc
• What safety measures should be taken during the experiment?

  Disinfect surfaces, wear protective gear
• Why is it important to wash hands after the experiment?

  To prevent contamination and spread of bacteria
• What should be avoided when sealing the petri dishes?

  Airtight seals to prevent anaerobic growth